Effect of different metal surface treatments and thermocycling on shear bond strength of heat cure and light cure at Co/Cr and Ni/Cr interface

Main Article Content

Ali M. Khursheed
Salah A. Mohammed

Abstract

Background Optimum bond strength at the metal – resin interface of prosthesis is essential for the success of that
prosthesis. The junction between metal alloy and acrylic resin is an area of clinical concern .Failure of a R.P.D. may
be linked to this interface. The main objective of this study were to determine the effect of different metal surface
treatment and thermocycling on the shear bond strength of Co/Cr alloy and Ni/Cr alloy to heat cure acrylic resin
and light cure acrylic resin.
Materials and methods: 120 metal samples were prepared, 60 Co/Cr samples and 60 Ni/Cr of square flat plate (30
mm x 30mm x 2 mm) that incorporated a central area (8mmx 12mm) of a large retentive mesh to simulate denture
framework. The samples were cleaned, finished and electropolished. Sixty samples of each type of metals were
divided into two groups according to the type of acrylic resin received each one 30 samples (A and group C) for
heat cure, B and group D for light cure) which were furtherly subdivided according to the type of surface treatment
into 3 subgroups each one 10 samples(A1 ,B1 ,C1and D1 )for no surface treatment, no thermocycling as a control
group (A2, B2 ,C2 and D2 )for Metal Prime II application with thermocycling (A3, B3 ,C3 and D3) for combination of
Air Abrasion and Metal Primer II application with thermocycling. The acrylic block were then prepared as a
rectangular block(12mm length ,8 mm width ,6 mm high )that was placed on a central area of metal plates, the
acrylic was fabricated in the same conventional way of denture construction. All the sample were mounted on
specially test fixture that would hold them rigid at a 90-degree angle from the horizontal plane of the crosshead of
the Instron machine .A tangent shear force was created by applying vertical load to the specimen .All of the
specimen were tested with Instron machine using stainless steel chisel shaped road at a constant crosshead speed of
5 mm min until failure of the bond occurred The specimen were stressed to failure .The force of bond failure was
recorded in Newton, which was divide by the surface of the bonded area (96 mm2 )to obtain the shear bond
strength calculated in Mpa.
Result: The results showed that the subgroup that received no surface treatment and without thermocycling for both
two type of resins heat cure and light cure (A1, B1, C1and D1) had the highest shear bond values, followed by
subgroups that received Air Abrasion + Metal Primer II surface treatments and thermocycling (A3, B3, C3,
D3).Subgroups that received Metal Primer II alone (A2, B2, C2 and D2) showed the least shear bond value than the
other subgroups.
Conclusion: All metal samples of Co/Cr and Ni/Cr with heat cure acrylic resin showed higher SBS mean values than
that light cure resin whether with surface treatment and thermocycling or without thermocycling concluded higher
binding of heat cure acrylic resin with the metal surface

Article Details

How to Cite
Khursheed, A. and Mohammed, S. (1) “Effect of different metal surface treatments and thermocycling on shear bond strength of heat cure and light cure at Co/Cr and Ni/Cr interface”, Journal of Baghdad College of Dentistry, 24(2), pp. 1-5. Available at: http://jbcd.uobaghdad.edu.iq/index.php/jbcd/article/view/1258 (Accessed: 29November2019).
Section
Restorative Dentistry